1. Field of the Invention
This invention relates to a shank chisel including a chisel head and a chisel shank. The chisel shank has a clamping sleeve in which the chisel shank is secured in captive fashion in a direction of a longitudinal axis and is able to rotate freely around its longitudinal axis.
2. Discussion of Related Art
Shank chisels of this kind are known. They are usually used in mining machines, road milling machines, and the like for stripping asphalt, rock, and the like. The shank chisels are mounted in chisel holders that are secured to a milling roller of the machine. The chisel holders have a bore acting as a chisel receptacle. The chisel shank is inserted with its clamping sleeve into the chisel receptacle. As a result, the clamping sleeve clamps against the inner wall of the chisel receptacle in a spring-elastic fashion. In the clamping sleeve, the shank chisel is secured in captive fashion in a direction of its longitudinal axis, but is able to rotate freely around its longitudinal axis.
When the tool is in use, a chisel tip secured to the chisel head is guided across the surface to be stripped and as a result, wears along with the chisel head. When the wear limit is reached, the shank chisel must be replaced. To overcome the clamping force of the clamping sleeve, an axial force must be introduced into the shank chisel. Various tools that can be used for this purpose are known from the prior art. For example, PCT International Publication WO 97/23710 discloses a tool in which a pin-shaped pushing section is coupled to a handle by an articulation. The tool is used for removing a shank chisel. To accomplish this, the pushing section is slid through the rear opening of the chisel receptacle and brought into contact with the free end of the chisel shank. The handle can then be swiveled until it comes into contact with a support section. Then in the articulation, the handle can be moved in relation to the pushing section. The pushing section introduces the resulting leverage forces into the chisel so that the locking of the clamping sleeve is released. When the shank chisel is removed and the tool is withdrawn, a new, unworn shank chisel can be placed against the receiving bore and driven into place with a hammer. With the known system, replacing a shank chisel is labor-intensive and cannot be carried out safely in cramped conditions.
German Patent Reference DE 30 26 930A1 discloses other detaching devices that require a ram, which is mounted in the region of the receiving bore for the shank chisel. The ram can be moved in linear fashion against the shank end of the shank chisel so that the latter can be moved out of the receiving bore.